1. Field of the Invention
The present invention generally relates to harvesting combines, and more particularly relates to harvesting combines having mechanisms for determining the amount of grain loss processed through the harvesting combine.
2. Description of the Related Art
A harvesting combine is a valuable agricultural tool which combines the functions of harvesting or gathering a crop with the function of separating the usable grain from the stalk in which the grain grows. The usable grain is collected and stored while the chaff, i.e., the stalk after the grain has been removed, is exhausted from the combine and thrown upon the field.
A typical combine includes a vehicle chassis with a pair of drive wheels driven by an engine, and a pair of steering wheels controlled by the operator. The operator is provided with an operator cabin. The front of the combine is provided with a header section, which is an elongate body disposed transverse to the longitudinal axis of the combine chassis and provided with a plurality of knives or shears which cut the grain stalks as the combine traverses a field to be harvested. The header is provided with an auger which draws the cut grain stalks into the header section and upward toward the body of the combine. A conveyor belt or similar conveying mechanism is then provided to transport the cut grain stalks from the auger of the header section to a thresher or threshing unit.
The threshing unit is often in the form of a rotating cylinder with a plurality of rasps or bars rotating within a barrel which thrash the cut stalks as it rotates. The usable grain is thereby removed from the grain stalks and is fed from the thresher unit to a mechanism for separating the usable grain from the chaff. The separating mechanism is often in the form of a vibrating sieve which has a plurality of apertures sized to allow the individual grain kernels to pass therethrough but which prevent passage of the chaff. The grain is thereby separated from the chaff and is conveyed to a storage bin or hopper also provided within the combine.
In order to remove the chaff from the top of the vibrating sieve, a blower fan is provided to direct a stream of air across the top of the vibrating sieve. The vibrating fan blows with enough force to carry the chaff off of the vibrating sieve and to an exhaust outlet at the back of the combine. The chaff is thereby removed from the combine and thrown onto the field being harvested.
With conventional combines, the blower fan blows an air stream across the sieve with a constant speed which is often sufficient to carry the usable grain along with the chaff out of the combine. This therefore results in grain loss and ultimately in lost profits. Combines are sometimes provided with adjustable speed blowers which allow the operator to increase or decrease the speed of the blower and thereby the force of the air stream across the sieve. For example, if the crop being harvested is particularly moisture-laden, then the crop will be relatively heavy and will require a stronger air stream to be removed from the sieve. However, in order to determine whether the blower fan is operating at a correct speed, the operator is forced to either place a container below the exhaust of the combine to gather the product being blown from the combine, or inspect the field directly behind the combine.
Both of these options have proven to be unacceptably inconvenient, expensive, or inaccurate. First, the act of collecting the product from the combine exhaust requires that a worker run along with the moving combine and place an object as well as the worker's body next to the moving combine. This is not only inconvenient and expensive in that it requires a worker in addition to the operator riding in the combine, but it has often proven to be a dangerous undertaking in that the worker running along with the combine is subject to being injured by the moving parts of the combine.
Second, the option of inspecting the field directly behind the moving combine has proven to be inaccurate. Since any combine will not gather 100 percent of the stalks and grain within a given field, a certain amount of grain will always be on the field directly behind the moving combine. Therefore, when the chaff and grain are exhausted from the moving combine, the grain thrown from the combine is mixed directly with the grain which was not gathered by the header in the first place. The operator or worker is therefore unable to differentiate between the grain being exhausted through the combine from that which was pre-existing on the ground.
The prior art has attempted to overcome these problems by providing combines with devices for monitoring the amount of grain loss processed through the combine. For example, one known system includes a combine grain loss monitor wherein the combine is provided with a primary separating sieve and a secondary separating sieve. As the grain is gathered through the header and processed through the thresher, the chaff and grain are separated through the primary sieve and the grain processed therethrough is collected for storage. The chaff and grain which are blown from the primary sieve are then conveyed to a secondary sieve rather than being exhausted from the combine. The secondary sieve again attempts to separate the usable grain from the unusable chaff with the unusable chaff being exhausted from the combine. The grain passing through the secondary sieve is then measured and a signal is fed to the operator's panel to indicate the amount of grain processed therethrough. If the amount of grain processed therethrough is beyond an acceptable limit, the operator can adjust the ground speed of the combine. However, such a device does not determine whether the speed of the sieve blower is set incorrectly, but rather only determines whether the ground speed of the combine is set incorrectly. Moreover, the addition of a secondary sieve and measuring device as well as the conveyance mechanism necessary for conveying the grain and chaff from the primary sieve to the secondary sieve adds considerable expense to the resulting combine.